/Engine/Source/Runtime/ApplicationCore/Public/GenericPlatform/GenericApplicationMessageHandler.h
Return true if this message handler expects FPlatformUserIds. This base class will convert both directions. As part of a larger fixup to allow mapping of multiple input devices to the same player, physical device id will be passed as part of the InputScope above and used to compute a logical input user.
virtual bool ShouldUsePlatformUserId() const